Utilization Zation Of Some Plant Oils In Producti On Of Butter Substitutes And Ke Pin6 Their Quality By Gamma Irradiation:

Ei-sayed Ahmed Mohamed Afifi

of this investigation was to study the possibility of using ablend 0 RBD palm oil and RBD stearin for production of butter substitutefree fr m cholesterol and trans fatty acids (formed due to hydrogenation ofoils which is used for production of butter substitutes or margarin) byblendin , and to study the possibility of using safe gamma irradiation dosesfor kee ing the quality of the product in comparison to the use of sodiumbenzoat a preservative.T~o parts of butter substitute samples were prepared. Samples ofIthe first part consisted of 58.31% RBD palm oil, 24.91% RBD stearin,0.25% e ulsefir, 12.4% boiled water, 2.4% dried skim milk, 1.5% sodium~ chloride, 0.3% sodium benzoate, 100 ppm of antioxidant (T.B.H.Q.) andbutter fl vour 2 mVkg. While samples of the second part were preparedfrom the same constituents without the addition of sodium benzoate. Then,samples of the second part were exposed to gamma irradiation at doses of2,4, 6 and 8 kGy (except some samples to serve as control samples).All samples were stored at both ambient and refiigeratortempera e. Attention was focused on the changes occurring in physicaland chern cal properties, fatty acid composition and Wlsaponifiable mattercomposit on as a result of either gamma irradiation or the addition ofsodium enzoate. In addition, the effects of these treatments onmicrobio ogical aspects by the determination of total counts of bacteriaand fun i. Moreover, the effect of these treatments on the organolepticpropertie of the product was studied by the evaluation of sensoryproperti s as appearance and colour and odour of samples at zero time andduring st rage for 60 days at ambient and refrigerator temperature.ts can be summarized as follows:1- Che1.1- e results of physico-chemical determinations showed the qualitypalm oil and palm stearin used in preparation of the product;they ad a melting point of 33 and 44°C, respectively. While, the acidvalue was 0.18 and 0.22 and the peroxide value was 0.35 and 0.42g for both palm oil and palm stearin, respectively.1.2- he results of physico-chemical determinations also indicated thegood physical and chemical properties for the product, the melting pointwas 5°C, while the acid and peroxide values were 0.245 and 0.451.3- e acid value of samples containing sodium benzoate did notchan ed and it was 0.23 , meanwhile, a slight gradual increase in theacid v ue was observed in the irradiated samples with the increase ofgamma irradiation dose; thus it increased from 0.24 in the controlsample to 0.28, 0.30, 0.33 and 0.36 in samples exposed to 2,4,6 and 8kGy, r spectively. In addition, the acid value showed a gradual increasein all amples during storage, but the rate of increase was lower in coldstorage than in storage at the ambient temperature.1.4- e peroxide value of samples containing sodium benzoate was notaltered compared to the control sample, while gamma irradiationtreatm nts caused a slight gradual increase in the peroxide value as itincrea ed from 0.45 meq/kg in the control sample to 0.94, 1.38, 1.6 and1.76 eq/kg in samples irradiated at 2,4,6 and 8 kGy, respectively.More ver, storage of samples either at ambient or at refrigeratortempe atore gradually increased the peroxide value in all treatments till30 da s of storage then, started to decrease gradually.1 5- e thiobarbituric acid (TBA) showed no changes as a result ofition of sodium benzoate compared to the control sample.M anwhile a very slight increase was observed in the TBA due toirr diation treatments. During storage, there were a gradual increasem e TBA values in all samples at both temperatures.1.6- he concentration of 100ppm T.B.H.Q. was the best one amongtested concentrations (0.0, SO,100, 150 and 200ppm) asrespectiv ly. p-sitosterol was the major sterol among sterol compoundsreaching 28.860/0. Gamma irradiation at 6 kGy did not cause detectablechange thesethe total hydrocarbons, total tocopherols and total sterols asompounds amounted to 15.52, 30.62 and 53.85 0/0,respecti ely, in the irradiated samples.2- Microt)iological analysis:-2.1- T e untreated butter substitute samples (control) had a highmicrob al load as the total bacterial and total mold counts were 3.2 x105 an 2.5 x 102 cfu/g, respectively.2.2- e control samples spoiled after IS and 30 days of storage atambie t and refrigerator temperature, respectively, as indicated by moldgrowt as well as the increase in both total bacterial and mold counts.2.3- he addition of sodium benzoate prevented the growth of bacteriaand olds in samples up to only 30 and 45 days of storage at ambientand r frigerator temperature, respectively.2.4- Irradiation doses of 2 and 4 kGy were not sufficient for keepingthe .crobiological quality of the product during storage since samplessubje ted to 2 kGy spoiled after 30 days of storage in both cases. Whilesam les irradiated at 4 kGy spoiled after 30 and 45 days of storage.2.5- amma irradiation doses of 6 and 8 kGy were sufficient andeffecti e for keeping the microbiological quality of the product all overth~ st rage period under investigation (60 days) at both temperaturesindicat g that 6 kGy dose was effective for keeping the product qualitywithou the need for cold storage.evaluation:-showed that there were no detectable changese general appearance and colour of butter substitute samples attime due to neither adding sodium benzoate nor treatment byrna irradiation. Although the original colour of the product did notalte ed during storage, the control samples were rejected because ofthe visual viewing of mold growth after 15 and 30 days of storage atand refrigerator temperature, respectively. Samplescon ining sodium benzoate were also rejected after 45 and 60 daysof torage at both temperatures, respectively. In addition, samplesina iated at 2 kGy were rejected for the same reason after 30 days ofsto ge at both temperatures, while samples subjected to 4 kGy dosewe rejected after 30 and 45 days.3.2- B tter substitute samples irradiated at 6 and 8 kGy dose kept theirsenso Quality for general appearance and colour allover the storageperiod3.3- S nsory evaluation also in.dicated that the odour of butter substituteles did as a result of adding sodium benzoate or irradiationents at the zero time. During storage, no rancid odour wasdet cted, but mody odour was detected in the samples which wererejected because of the presence of mold growth (control, samplescontaining sodium benzoate, samples irradiated at 2 and 4 kGydoses). In addition, samples irradiated at 6 and 8 kGy kept theirodour quality allover the storage period either at ambient orrefrigerator temperature.